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Discussion Starter #1
Hello,
My house has a basic Hunter 42999b thermostat. The house was built in 1938, so I'm sure there were many shortcuts to sell.

The rubbery external up/down thermostat buttons stopped working a WHILE ago, but the "switch" click options within worked (heat/cool & auto/fan).

But now I can't switch it on the "cool" function at all. The digital screen doesn't show "cool" when I adjust it.:wallbash::

The fan option works. So it's getting SOME power, right?

I ordered the same thermostat online, just for a quick replacement. But it won't get here for a while. IT'S GETTING HOT in Dallas. lol.

Any advice??

Thanks in advance :vs_cry:
 

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The Hunter thermostat you have is very basic and doesn't require a C (common) wire to operate. You could go to Lowes/HD tonight and get a basic heat/cool programmable thermostat that will work without the C wire. Send the Hunter back when you get it, the one from the store will probably be better.
 

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Discussion Starter #5
It's tough bc I have a LARGE shepherd dog in the house when I go to work, so I'm EXTRA concerned about having no AC

Really want to fix it as soon as possible
 

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You could remove the thermostat and jump out the wires that are connected to the R and Y terminals on the thermostat. The outdoor unit should turn on, if so, you definitely need a new thermostat, which will also take care of your non working up/down buttons.



If you want to follow SeniorSitizens suggestion for temporary relief, turn off power to the unit and jump out (connect together) the R, Y and G wires at the thermostat, turn power back on, the fan and outdoor unit should run. Warning, you unit won't shut off so you can't leave it running all night.
 

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Should be able to just go get a thermostat at a hardware store.
Some will require a common. Others will require batteries if no common is used.
 

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Discussion Starter #9
I did order a new thermostat...it's just going to take several days to get here ;)
And it's pretty hot in Dallas right now!

Yes, batteries replaced w solid Duracells. Nothing happened.

SO, 57, I could jump start the wires... I do have the little wire to connect the two...I think that's my next move, also according to YouTube...just can't connect the wrong wires, right?
 

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You could definitely connect the wires wrong if you're not paying attention.
Turn off power to the unit (furnace?). Remove the thermostat and note what color wire goes to what terminal. You probably have terminals RC/RH, Y, W and G.
RC/RH = power
Y = cool
w = heat
g = fan


Typically, wire colors correspond to the terminals ie: RC/RH (red), w (white)
y (yellow), g (green) but not always. Just make sure to jump out the wires that are on the Rc/RH, Y and G terminals, these 3 wires need to be connected together. Don't forget to turn the power back on.


If your just testing the thermostat just jump out RC/RH to Y that should turn on the outdoor unit. Connect the G wire too if you want actual temporary cooling.
 

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Discussion Starter #12
Should I manually reconnect the wires or just do the jump?

It's sort of disconcerting either way :confused1:
 

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Whatever is easiest for you to do. Don't worry, I don't think a large mushroom cloud will be forming over Dallas in the next few minutes.
 

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Not sure what your CV19 situation is there in Dallas but Lowes and Home Depot have plenty of thermostats in stock. Probably even smaller outlets like Ace Hardware. No need to wait to get one.
 

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My house was built in 1946 concrete brick house I brought it in 1997 and 1998 I replace the whole system with new 5 tons runs perfect till DEC, 2019 try turn the heat on but it does not work, I consult online and try turn furnace power off ( power will be off once the cover plate of furnace remove a safety switch will automatically turn power off) in attic then jump wire R to W which means connect R power to W heater, afterward I used Tape to press the switch back ON so Fan blower turn on for 10 second then off wait 1.5 minutes my furnace ON and fan blower ON but when I took the jumper cable off and try jump it from my thermostat, it burnt my 24 VAC transformer because of the thermostat wire ( 5 wire ) was short between furnace and thermostat, I managed to replace a new thermostat wire then heat and cool all work fine. wire short is the common problem occur in HVAC system to make it not work,
 
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